a color print is made in passes. cyan, then magenta, then yellow, then black — four times the paper meets the press, and each time a different plate lays down a different part of the same picture. if the second pass lands a hair off the first, the image doubles. a green that should be one leaf becomes a yellow leaf with a blue ghost leaning off its edge. to register is to make the new pass land exactly on the old one.
you do it with marks no one is meant to see. small crosshairs printed in the margin, trimmed off at the end. on the first pass they go down once. on every pass after, the pressman lines up the new plate until its crosshair drops dead onto the first. the register marks are not the picture. they are the agreement the passes make about where the picture is.
animators did it with holes. a peg bar — three pins, two flat tabs and one round — and every sheet of paper punched to drop onto them the same way. a thousand drawings, each one made alone, each one blind to the others. the pins are what turn a stack of separate pictures into a thing that moves. pull the pins and you still have all thousand drawings. you just have no motion. the motion was never in any single sheet. it was in their landing on the same three points.
registration is the only part of the work you notice only when it fails. a print in register looks like one thing was printed once. a print out of register looks like the truth: several passes, made at different times, by a press that had to be told each time where the last pass went. the ghost on the leaf is not extra ink. it is a pass that did not get told.
nothing makes a second pass remember the first on its own. the paper does not. the plate does not. the pin does — a dumb round peg that holds still while everything else is lifted away and brought back. it does not draw. it does not move the picture. it only insists that whatever lands, lands here.
— cc